CEL P0201/P0301 (fuel injector/misfire) - but only on return trips?

[lando66]

Greetings everyone. First time poster here (and I have searched to see if my issue has previously been discussed with no luck).

Here is my issue that I would be grateful if anyone has any suggestions:

I have a 2008 Liberty with 222k miles. I am getting a CEL that is throwing P0201/P0301 (cylinder #1 fuel injector/misfire). Here is the mystery.

The first drive of the day, I can drive for miles/hours without the CEL coming on. All is well and the engine runs smooth. If I stop the car and restart it - whether that was after a 5 minute drive or a 2 hour drive, the CEL will come on, throw the codes, and the engine runs noticeably rougher. If I let it sit for a day or two, I can clear the codes and it will start up just fine again without throwing the codes (until I stop and restart...)

Since I can drive for hours without the CEL coming on, it doesn't seem to me like it is actually the fuel injector or the electrical connection - but willing to be told otherwise. I have checked the wire connector to the injector, and do not see any obvious issue there.

How could things be "perfectly fine" out of the driveway during the first use of the Jeep, but throwing the codes and running rough on the restart/return trip no matter what the length of the outbound trip was? (and how can I diagnose/troubleshoot?)

Thanks in advance for any help/suggestions!

 

[LibertyTC]

Welcome.
How many miles on the KK?
Interesting that only the #1 cylinder/ misfire- possibly indicating a dirty injector with questionable spray characteristics.
Have you tried an injector cleaner? Get some Chevron Techron Concentrate additive -2 bottles and add that to the fuel, and see if that helps.
Next..I would recommend a psi fuel pressure test to ensure correct fuel pressure. There also must be a fuel filter on the KK...

 

[lando66]

Thank you for the response.

There is just over 222k. I also changed the spark plugs and the coils (originals) when I first got the codes - concentrating on the P0301.
Just put some injector clearer in the other day when I filled up - probably only have 1.5 hours of run time with it added. Plan was to put a bottle in for 2 fill ups and see if that does the trick - but wanted to lean into where to go next if that doesn't work.

 

[LibertyTC]

What spark plugs did you install ? Always refer to your owners manual, hopefully you used: NGK ZFR6F-11 (Gap.043 in)

 

[lando66]

No - I used Bosch Iridium Spark Plugs (9604) - which are supposed to be compatible. Looks like the gap is pre-set to 0.040. That being said - I was getting the codes before I changed the plugs/coils

 

[LibertyTC]

No - I used Bosch Iridium Spark Plugs (9604) - which are supposed to be compatible. Looks like the gap is pre-set to 0.040. That being said - I was getting the codes before I changed the plugs/coils

Jeep is very picky over spark plugs.
Use the copper core ngk model as mentioned above.
Jeep will run better and say thank you!